Nondestructive evaluation (NDE) of cylindrical containers is of critical importance because of their ubiquity in industrial applications. However, there is a paucity of research on the NDE of solid cargo inside sealed enclosures with external sensors. This talk covers the application of linear and nonlinear resonance spectroscopy to the NDE of cargo inside cylindrical containers. The first study focused on a Transnuclear-32 (TN-32) cask used for the dry storage of spent nuclear fuel assemblies. The modes of the TN-32 were measured onsite and Finite Element Analysis was used to investigate modal changes due to loadings of fuel assemblies. Because of the difficulties introducing damage to fuel assemblies inside a TN-32, a 1:6 scaled cask containing 32 mock-up fuel assemblies was manufactured for laboratory studies. Using the linear approach, metrics were developed that could detect cargo damage down to the single assembly level. To resolve the signatures of damaged versus missing assemblies, nonlinear ultrasound resonance spectroscopy was utilized to investigate the contact nonlinearity between a smaller scale container and loose spheres which mimicked internal debris. Based on the resulting data, a phenomenological contact-loss model was developed which could estimate the total mass of the spheres regardless of the material and radius.
The assessment of the internal structural integrity of dry storage casks for used high burnup nuclear fuel assemblies is of critical importance before these are transported to permanent repositories. The size of the casks (5.2 m in height and 2.4 m in diameter), structural complexity, and the inability to access the interior make this a challenging task. This project addresses these difficulties through a multi-modal approach involving nuclear, charged particle, and acoustic methods. In this talk, we report on linear and nonlinear vibrational spectra of intact TN-32 casks. These studies use both impulsive and swept continuous-wave excitations with a variety of sensor placement configurations. From the resulting spectra, resonant frequencies, quality factors, and harmonic responses of various vibrational modes were determined. A detailed finite element model of the TN-32 was constructed and the experimental results are compared to the modal structure determined numerically. [This work was supported by DOE NEUP Award: DENE0008400.]
The assessment of the internal structural integrity of dry storage casks for used high burnup nuclear fuel assemblies is of critical importance before these are transported to permanent repositories. The size of the casks (5.2 m in height and 2.4 m in diameter), structural complexity and the inability to access the interior make this a challenging task. This project addresses these difficulties through a multi-modal approach involving nuclear, charged particle and acoustic methods. In this work, we report on measurements of the vibrational spectra and mode shapes using a 6:1 scaled TN-32 model cask constructed in our lab. 2-D vibrometric scans were performed with a laser Doppler velocimeter to measure the vibrational mode shapes exhibited by the cask. Good agreement is observed between the experimentally measured mode shapes and those determined numerically using a detailed finite element model. Several modes are identified that will be important in assessing the internal characteristics from external measurements. [This work was supported by DOE NEUP Award: DENE0008400.]
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